Amid China's current fascination with military symbols, some of the country's most important new heroes are serving in a little army unit called the Hard-Bone 6th Company.

Party Chairman Hua Kuo-feng who himself has taken to appearing occasionally in army uniform, has joined his number two party leader and defense minister, Yeh Chien-ying, in calling for an "extensive mass movement" to emulate the company. The Hard-Bone 6th carries the message of the new year: less talk, more action.

After years in which Chinese soldiers were praised for the long hours they spent reading the works of Chairman Mato Tse-tung, the Hard-Bone 6th is instead congratulated for its attention to target bulletins are beginning to suggest something that would have been considered heresys six months ago - that people should spend fewer hours discussing their political thoughts and more hours in the fields and factories.

This indicates the Chinese are worried about the combat readinesss of their troops. It also means that they see a return to fundamental soldiering as a way to chastize those younger army officers who backed the former emphasis on political training as a way to show up their battle-scarred senior officers.

The same message to youth is being emphasized even more strongly in a companion campaign to revive study of the life of Lei Feng, a soldier hero who died in 1962 and is praised for the socialist enthusiasm he put into even the most menial chores.

This appears to be bad news for the former darlings of the Chinese army, the "Good 8th Company of the Nanking Road," a unit that has seen its stock plunge as the party leaders of its base in Shanghai, who put political training above all, have been purged by the post-Mao leadership.

"The commanders and fighters of the Good 8th Company have deeply understood that without laying hold of the sharp ideological weapon, they cannot fight," a 1974 People's Daily article said with approval. "They kept a very tight grip on study and combined study with discussion and criticism."

By contrast, the New China News Agency recently praised China's new army heroes by saying: "Keeping in mind Chairman Mao's teaching that the People's Liberation Army is always a fighting force, commanders and fighters of the 6th Company have trained hard to master military skills. During the past 13 years, they have carried out 79 live shell practices, of which 68 yielded good results."

Hua and his colleagues appear to want China to concentrate on symbols, like the Hard-Bone 6th, while they work out the knotty practical problems of how to purge the disgraced followers of Mao's widow Chiang Ching and how to utilize old cadres whom Chiang had forced to retire like former Vice Premier Teng Hsiao-ping. A few reports of anti-Chiang rallies and mass trials in places like Wuhan and appointments of new party chiefs in some provinces suggest that Hua is moving selectively and slowly.

In vast areas of China, including Hua's political base in Hunan, it is, after all, time to plant rice. This slows down political developments and leads provincial radio broadcasts to exhort all hands, soldiers and peasants, to get out to the fields.

"It is necessary to hold less and more concise meetings," said a Hunan broadcast monitored here Feb. 27. "During the busy season of spring farming, we should in general not hold meetings. Necessary meetings must be small and brief."